Looks like scrolling a long web page in Safari has just gotten better. After a few flicks, the travel will increase. It's somewhat similar to the Page Up/Down Key kicking into action.
Edit: It's a system-wide thing. Any app that has a long list will have it. Try it in Settings > General > About > Legal.
Edit: It's a system-wide thing. Any app that has a long list will have it. Try it in Settings > General > About > Legal.